A method of forming a solder bump may involve forming a first photoresist pattern on a wafer having a pad. The first photoresist pattern may have an opening that exposes a portion of the pad. A first under bump metallurgy (UBM) layer may be formed on the pad, and a second UBM layer may be formed on the first photoresist pattern. A second photoresist pattern may be formed that exposes the first UBM layer. A solder bump may be formed in the opening. The second photoresist pattern and the first photoresist pattern may be removed using a stripper, thereby removing the second UBM layer by a lift-off method.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of forming a bump, the method comprising: forming a passivation layer on a wafer having a pad, such that the passivation layer exposes a portion of the pad; forming a first photoresist pattern on the passivation layer, the first photoresist pattern having a first opening that exposes the pad; forming a first under bump metallurgy (UBM) layer on the pad; forming a second UBM layer on the first photoresist pattern; forming a photoresist layer over the first and the second UBM layers; forming a groove in the photoresist layer so as to expose the second UBM layer by exposing and developing the photoresist layer; etching the second UBM layer exposed by the groove; forming a second photoresist pattern by re-exposing and re-developing the photoresist layer disposed on the first UBM layer to form a second opening that extends from the first opening; forming a solder bump in the first and the second openings; and applying a stripper into the groove to remove the second photoresist pattern and the first photoresist pattern, thereby removing the second UBM layer by a lift-off method.
2. The method of claim 1 , wherein the groove is spaced apart and separate from the first opening.
3. The method of claim 1 , wherein the groove surrounds the first opening.
4. The method of claim 1 , wherein the first opening exposes the pad and the passivation layer in the vicinity of the pad.
5. The method of claim 4 , wherein the first UBM layer is adjacent to the first photoresist pattern and the passivation layer.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
September 29, 2006
June 30, 2009
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